Research On Safety Risk Assessment Of The Existing Bridge In The Drought And Cold Region Of North-West China

With the rapid development of China’s transportation industry,highway bridges bear the increasingly heavy traffic tasks,most of the bridge’s use function has been unable to meet the current requirements,which has become a bottleneck in transportation,restricting rapid development of China’s economic construction,and even lead vicious incident that seriously affecting the safety of people’s lives and property.Therefore,it is necessary to study the safety performance of the existing bridges and carry out safety risk assessment of the existing bridges.Arch bridge has an important position in the history of the development of China’s bridge,a large number of arch bridge play a role in the traffic at present,and it also has broad application prospects in the infrastructure construction of future,so put the arch bridge as a typical case,and focuses on the safety risk assessment of the existing arch bridge in the drought and cold region of northwest China,it mainly includes the disease identification of the arch bridge,the establishment of the index system,the establishment of the membership function,the determination of the evaluation criteria and so on,establishes a scientific and reasonable safety risk evaluation system for the existing bridge to determine whether it will appear security risks during use.The paper consists of four parts.By extensive inspection on the research results in the field of risk and bridge safety,ascertain the research method of bridge safety risk assessment system is to apply the theory and method of risk assessment to the bridge safety state assessment,through the comprehensive evaluation of the damage of the existing bridge,it can determine whether the safety performance can meet the current requirements.Analyses the common methods of risk assessment,sums up their principles,scope of application,shortcomings,and selects the methods applicable to bridge safety risk assessment.Analysis the data of 145 arch bridges in Gansu Province,based on the structural characteristics of the arch bridge and the characteristics of the reinforced concrete material,identifies the common diseases and their causes of the existing arch bridge in the drought and cold region of north-west China,forms the evaluation indexes,and establishes the safety risk assessment index system.The index system is divided into three layers,the first layer is the target layer,that is,the safety risk of the existing bridge in the drought and cold region of north-west China,the second layer is the structural layer,including the main arch,arch structure,abutment,pier,foundation and bridge deck system,the third layer is the bottom of the index system,formed by the apparent manifestations of the disease,such as the main arch cracks,piers displacement,base erosion and so on.The index system can be comprehensive reflection the common risk factors of the existing arch bridge in the drought and cold region of north-west China,and rich hierarchical.Expatiates on the detailed steps of using the fuzzy comprehensive evaluation method to carry out the safety risk assessment of bridge.The safety risk of the existing arch bridge in the drought and cold region of north-west China is divided into four grades,and the evaluation criteria of each index are established.For the numeric indicators,the membership function is established by using the trapezoidal distribution which is more commonly used in the F distribution,and then calculates the degree of membership of each index.For the descriptive indicators,the evaluation level vector of each index is given directly through the qualitative description of its completeness according to the relevant specification.Taking an arch bridge on the Ding-Long highway in Gansu province as an example,based on the proposed index and index evaluation criteria for the existing arch bridge in the drought and cold region of north-west China,the fuzzy comprehensive evaluation method is used to evaluate the safety risk of the bridge,and the corresponding risk response measures are given.The evaluation results are in good agreement with the actual situation,and the rationality of the method is verified.The application of research results in the field of risk assessment can be used to provide the basis for the maintenance and reinforcement of the bridge,and to expand the research field of bridge risk assessment,which is beneficial to the research of bridge risk to the deeper and higher level theory and practice direction.